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1. Indication & Clinical Context
1b. Suggested Sequence, Probe Principle & Core Objectives
StepTargetTypical teaching time*
1Subcostal cardiac: RV/LV relationship, gross LV function, pericardium60–90 s
2IVC: anatomy and respiratory behavior as contextual data30–45 s
3Lung: sliding, A/B-line pattern, consolidation/effusion as indicated60 s
4FAST / aorta / venous screen when clinically indicated30–60 s
5PLR + LVOT VTI when fluid responsiveness remains clinically importantVariable

*Approximate teaching targets after competency, not a validated universal completion time. The sequence may be reordered according to the suspected immediately reversible cause and patient stability.

Core objectives

  • Identify immediately important obstructive causes: tamponade, tension pneumothorax and major RV pressure overload/possible PE.
  • Characterize gross LV and RV systolic function and chamber relationships.
  • Look for pulmonary interstitial syndrome, pleural effusion, consolidation and pneumothorax-related signs.
  • Assess venous filling/IVC behavior as one contextual variable rather than a stand-alone volume or fluid-responsiveness test.
  • When a fluid challenge is being considered, determine whether a reversible preload challenge produces a meaningful increase in forward flow and whether the lungs appear tolerant of additional fluid.
  • Repeat POCUS after major therapeutic interventions when the clinical question persists.
2. Step 1 — Subcostal Cardiac Window 60–90 s

Probe position: subxiphoid/subcostal, using the liver as an acoustic window. Obtain a subcostal four-chamber view when possible.

2b. Teaching Notices
3. Step 2 — IVC Assessment 30–45 s

Context, not a stand-alone fluid test. Obtain a longitudinal subcostal IVC view with the vessel entering the right atrium; measure perpendicular to its long axis at a consistent site. A high-quality B-mode cine loop is often preferable to M-mode alone for confirming anatomy and avoiding off-axis measurements.

Confounders present

3b. Evidence Note

Major confounders include spontaneous respiratory effort, mechanical ventilation settings, right-heart failure, tricuspid regurgitation, pulmonary hypertension, tamponade, intra-abdominal hypertension, elevated PEEP, severe COPD/auto-PEEP and altered venous compliance. When these are present, prioritize dynamic flow-based assessment when feasible.

4. Step 3 — Lung Ultrasound 60 s

Use the same curvilinear/microconvex probe when image quality is adequate. A limited screen is appropriate during immediate resuscitation; extend posteriorly and complete the examination when the diagnosis remains uncertain.

Aggregate lung pattern and pneumothorax/effusion/consolidation flags are computed live in the decision-support cards above.

4b. Teaching Notices
5. Step 4 — Abdominal / Vascular Screen 30–60 s, if indicated

Perform FAST views, abdominal aortic screening or focused venous assessment only when clinically indicated. The curvilinear probe is well suited to these deeper examinations.

5b. Interpretive Cautions
6. Step 5 — Fluid Responsiveness: PLR + LVOT VTI Variable

Fluid responsiveness means an increase in cardiac output or stroke volume after a preload increase — it does not mean the patient requires fluid.

PLR/LVOT VTI interpretation is computed live in the decision-support cards above.

6b. Technical Requirement & Evidence
7. Clinician-Confirmed Phenotype & Plan

Auto-suggested phenotype, fluid tolerance and PLR interpretation appear in the decision-support cards above — decision-support only, not a diagnosis.

Post-scan checklist

7b. Shock Phenotyping Decision Matrix (reference)
Working phenotypeTypical POCUS patternManagement implication
Hypovolemic / low fillingSmall/hyperdynamic LV, low venous filling, A-line-predominant lungs, compatible historyConsider a monitored fluid challenge if a therapeutic indication exists; treat the cause of volume loss
DistributiveHyperdynamic or preserved LV, variable venous findings, A-line or source-specific lung patternTreat infection/vasodilation/other cause; use dynamic assessment to determine whether fluid is likely to help
CardiogenicLV systolic dysfunction and/or major valvular/cardiac abnormality, pulmonary congestion, venous congestionAvoid routine empiric fluid loading; prioritize cause-specific cardiac management and perfusion support
ObstructiveTamponade physiology, major RV pressure overload/possible PE, or pneumothorax-related findingsUrgently evaluate and relieve the obstruction; do not delay definitive management for serial POCUS
MixedMore than one phenotype simultaneouslyTreat the dominant immediately reversible physiology and reassess dynamically
7c. Evidence-Based Teaching Pearls & Limitations
  • A curvilinear/microconvex probe is a versatile shock POCUS probe, not a universal replacement for every ultrasound transducer.
  • IVC size and respiratory variation are contextual findings; do not use them as an isolated prescription for fluid.
  • PLR coupled to a flow variable is substantially more robust than static volume surrogates for testing preload responsiveness.
  • B-lines indicate an interstitial syndrome; they do not by themselves diagnose cardiogenic pulmonary edema.
  • Absent lung sliding is not synonymous with pneumothorax; look for a coherent pleural pattern and, when possible, a lung point.
  • RV enlargement is not synonymous with acute PE and should be integrated with the clinical probability and other POCUS findings.
  • Fluid responsiveness is a physiological property. Fluid requirement is a treatment decision.
  • Serial, integrated reassessment is more defensible than a one-time threshold-driven decision.

Limitations

  • Probe: less optimal cardiac temporal/superficial resolution than a phased-array probe; less suitable for superficial structures than a linear probe.
  • Window: severe obesity, bowel gas, abdominal distension, dressings, subcutaneous emphysema and prior surgery may prevent adequate subcostal imaging.
  • IVC: diameter and respiratory variation are strongly affected by ventilation, respiratory effort, right-heart pathology and intra-abdominal pressure.
  • Lung: B-lines and absent lung sliding are pattern findings, not single-diagnosis findings.
  • Operator dependence: all focused ultrasound findings depend on acquisition quality and interpretation. Residents should obtain supervised competency before using quantitative measurements for management.
  • Doppler: VTI is highly dependent on alignment, sample location and beat selection. Poor alignment should be reported as a limitation rather than converted into a false numerical value.
  • PE: RV enlargement is supportive but non-specific. POCUS cannot reliably exclude PE in isolation.
  • Tamponade: pericardial effusion is not synonymous with tamponade. Chamber collapse and hemodynamic context matter.
  • Time: ≈5 minutes is a training target for a core screen, not a validated universal completion time.
References
  1. Andruszkiewicz P, Sobczyk D, Nycz K, et al. A comparison of the ultrasound measurement of the inferior vena cava obtained with cardiac and convex transducers. Journal of Ultrasonography. 2017;17:241–245. PMID: 29375898. PMCID: PMC5769663. DOI: 10.15557/JoU.2017.0035.
  2. Lichtenstein DA. How can the use of lung ultrasound in cardiac arrest make ultrasound a holistic discipline. The example of the SESAME-protocol. Medical Ultrasonography. 2014;16:252–255. PMID: 25110767. DOI: 10.11152/mu.2013.2066.163.dal1.
  3. Lichtenstein D, Malbrain MLNG. Critical care ultrasound in cardiac arrest. Technological requirements for performing the SESAME-protocol—a holistic approach. Anaesthesiology Intensive Therapy. 2015;47:471–481. PMID: 26578398. DOI: 10.5603/AIT.a2015.0072.
  4. Lari A, et al. Inferior Vena Cava Ultrasonography for Volume Status Evaluation: An Intriguing Promise Never Fulfilled. Journal of Clinical Medicine. 2023. PMCID: PMC10053997.
  5. Cardozo Júnior LCM, Lemos GSDL, Besen BAMP. Fluid responsiveness assessment using inferior vena cava collapsibility among spontaneously breathing patients: Systematic review and meta-analysis. Medicina Intensiva. 2023;47:90–98. PMID: 36272909. DOI: 10.1016/j.medine.2021.12.018.
  6. Islam M, Levitus M, Eisen L, Shiloh AL, Fein D. Lung Ultrasound for the Diagnosis and Management of Acute Respiratory Failure. Lung. 2020 Feb;198(1):1-11. DOI: 10.1007/s00408-019-00309-1.
  7. Lichtenstein DA, Mezière GA, Lagoueyte JF, et al. A-lines and B-lines: lung ultrasound as a bedside tool for predicting pulmonary artery occlusion pressure in the critically ill. Chest. 2009;136:1014–1020. PMID: 19809049. DOI: 10.1378/chest.09-0001.
  8. Díaz-Gómez JL, Sharif S, Ablordeppey E, et al. Society of Critical Care Medicine Guidelines on Adult Critical Care Ultrasonography: Focused Update 2024. Critical Care Medicine. 2025;53:e447–e458. PMID: 39982182.
  9. Cherpanath TGV, Hirsch A, Geerts BF, et al. Predicting Fluid Responsiveness by Passive Leg Raising: A Systematic Review and Meta-Analysis of 23 Clinical Trials. Critical Care Medicine. 2016;44:981–991. PMID: 26741579. DOI: 10.1097/CCM.0000000000001556.
  10. Cavallaro F, Sandroni C, Marano C, et al. Diagnostic accuracy of passive leg raising for prediction of fluid responsiveness in adults: systematic review and meta-analysis of clinical studies. Intensive Care Medicine. 2010;36:1475–1483. PMID: 20502865. DOI: 10.1007/s00134-010-1929-y.

Program: RS-POCUS (Rapid Shock POCUS) v1.0. Author: Prof. (Dr) Jyotirmay Kirtania. Copyright: © 2026 Prof. (Dr) Jyotirmay Kirtania. License: GNU General Public License version 3.0 or later (GPL-3.0-or-later).